Unexpected formation of nitroso-chelated cyclic η1-acylruthenium(II) complex, an effective catalysts for transfer hydrogenation reaction

Article abstract of DOI:10.1016/j.jorganchem.2018.01.035

Reaction of commercial ruthenium complexes M31 and M20 with 2-nitrostyrene gave a new nitroso-chelated cyclic η¹-acyl ruthenium(II) complexes Ru-4 and Ru-6 respectively instead of expected Hoveyda-Grubbs type (pre)catalyst Ru-3. New complexes w

Full text of DOI:10.1016/j.jorganchem.2018.01.035

Accepted Manuscript
Unexpected formation of nitroso-chelated cyclic η1-acylruthe-nium(II) complex, an
effective catalysts for transfer hydrogenation reaction
Nirmalya Mukherjee, Rafał Gawin, Stefan Czarnocki, Roman Gajda, Maura Malińska,
Krzysztof Woźniak, Anna Kajetanowicz, Grela Karol
PII:
S0022-328X(18)30041-X
10.1016/j.jorganchem.2018.01.035
JOM 20273
DOI:
Reference:
To appear in: Journal of Organometallic Chemistry
Received Date: 14 November 2017
Revised Date: 19 January 2018
Accepted Date: 20 January 2018
Please cite this article as: N. Mukherjee, Rafał. Gawin, S. Czarnocki, R. Gajda, M. Malińska, K.
Woźniak, A. Kajetanowicz, G. Karol, Unexpected formation of nitroso-chelated cyclic η1-acylruthe-
nium(II) complex, an effective catalysts for transfer hydrogenation reaction, Journal of Organometallic
Chemistry (2018), doi: 10.1016/j.jorganchem.2018.01.035.
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ACCEPTED MANUSCRIPT
OH
transfer hydrogenation
MesN
Cl
NMes
O
N
TsN
Ru
R
cycloisomerization
ROMP
O
R = PPh3, Py
n
MeOOC
COOMe
Unexpected ruthenium complexes for transfer hydrogenation, cycloisomerization, and ring opening
metathesis polymerization.

ACCEPTED MANUSCRIPT
Unexpected formation of nitroso-chelated cyclic η1-acylruthenium(II) complex, an effective
catalysts for transfer hydrogenation reaction
Nirmalya Mukherjee, Rafał Gawin,‡ Stefan Czarnocki, ‡ Roman Gajda, Maura Malińska,
Krzysztof Woźniak, Anna Kajetanowicz,* Karol Grela*
Biological and Chemical Research Centre, Faculty of Chemistry, University of Warsaw, Żwirki i
Wigury 101, 02-089 Warszawa, Poland
‡ Current address: Apeiron Synthesis S.A., Duńska 9, 54-427 Wrocław (Poland)
This paper is dedicated to Professor Irina P. Beletskaya on the occasion of her 85th birthday.
ABSTRACT: Reaction of commercial ruthenium complexes M31 and M20 with 2-nitrostyrene
gave a new nitroso-chelated cyclic η1-acyl ruthenium(II) complexes Ru-4 and Ru-6 respectively
instead of expected Hoveyda-Grubbs type (pre)catalyst Ru-3. New complexes were characterized
by means of standard analytical techniques and their crystallographic structure has been
confirmed by X-ray structural analysis. It was found that Ru-4 and Ru-6 do not exhibit any
activity in standard metathesis reactions. However, a dramatic increase of activity was observed
upon treatment with (trimethylsilyl)diazomethane, allowed for the successful application of Ru-4
in ROMP of endo,exo-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid dimethyl ester. Moreover,
such complexes can be effective catalysts of transfer hydrogenation of ketones as well as
cycloisomerisation reactions.
KEYWORDS: Olefin metathesis, transfer hydrogenation, cycloisomerization, ring opening
metathesis polymerisation (ROMP), racemisation, ruthenium
Introduction
Transition metal complexes have been used in plethora of chemical transformations for
decades [1-4]. Particularly noteworthy are the ruthenium-based complexes which can catalyse
numerous different reactions. One of the most important transformations occurring in the
presence of ruthenium compounds is olefin metathesis, a reaction intensively studied for years [3,
4], especially after 2005, when Yves Chauvin, Robert H. Grubbs and Richard R. Schrock
received the Nobel Prize in Chemistry [5]. One of the main development directions of this
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methodology is the research conducted on obtaining new, more active and selective catalysts,
often for specialized applications such as ethenolysis [6, 7], self-cross metathesis of α-olefins [8,
9], or stereoselective synthesis of products with E [10, 11] or Z [12, 13] configured double bonds.
In our previous research we studied the Hoveyda-Grubbs second generation catalyst’s
analogues containing nitro group in the benzylidene fragment. The most active was a complex
Ru-1 containing NO2 substituent in para position to isopropoxy group (Figure 1) [14]. As this
complex was highly active in the case of so-called "difficult substrates" (belonging to the olefin
types II [14, 15] or III [14-17] according to the Grubbs classification [18], as well as toward
substrates sensitive to harsh reaction conditions) [19] and was later used in a number of target-
oriented synthesis and commercialized [20], we decided to look for its analogues. The catalyst
with nitro group in meta position to isopropoxy group was also obtained (Ru-2, Figure 1) and
shown similar activity to its para analogue, but due to more complicate synthesis it was not
commercialized. In the present study, we wanted to obtain a complex Ru-3 in which the nitro
group located in the ortho position to the double bond in benzylidene ligand would be on one side
an electron-withdrawing group and at the same time would form a chelate with a ruthenium atom
(Figure 1). To our surprise we did not get the desired complex but instead we obtained ruthenium
complex destitute benzylidene ligand, which demonstrated activity in transfer hydrogenation and
other reactions.
MesN
NMes
MesN
NMes
MesN
Cl
NMes
Cl
Cl
Ru
O
Ru
O
Ru
Cl
Cl
Cl
O
NO2
N
O
NO2
chelating activating
group group
chelating
group
chelating & activating
group
activating
group
planned
known
Figure 1. Known and planed complexes bearing NO2 group in different positions in benzylidene
ligand (Mes = mesityl group).
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Results and discussion
Reaction of indenylidene ruthenium complexes M31 and M20 with 2-nitrostyrene
We attempted to synthesize the catalysts Ru-3 according to well established methodology,
previously used for synthesis of its analogues bearing NO2 group in different positions in
benzylidene ligand (Scheme 1) [14].
Scheme 1. Synthesis of complex Ru-4. Conditions: toluene, 80°C, 5 min.
To do so, we mixed 2-nitrostyrene with the third generation indenylidene catalyst (Umicore
M31) in toluene at 80°C and stirred the mixture until the substrate disappeared completely. To
our surprise instead of expected product Ru-3 we obtained a new benzylidene-deprived
ruthenium complex Ru-4. Spectroscopic techniques and X-ray crystallographic analysis showed
that the major product obtained in 48% yield is a nitroso-chelated cyclic η1-acylruthenium(II)
complex Ru-4 (Figure 2), however single crystals of this compound were of low quality and they
were diffracting X-ray radiation very poorly. In consequence the quality of the structure Ru-4 is
not too high. The obtained thermal parameters are accompanied by a quite high residual peak at
the centre of the N-heterocyclic ring indicating possible twining for the single crystal used for
data collection. Unfortunately, the quality of data was too poor to resolve twinning. The
presented structure was solved and refined against reflection data of the main component which
consists of ca. 82% of all collected reflections.
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Figure 2. Crystallographic structure of the complex Ru-4 (one of two molecules in the
asymmetric part of the unit cell). Selected bond lengths in angstroms [the corresponding bond
lengths in the second molecule in brackets]: Ru1-Cl1 2.421(2) [2.418(2)], Ru1-C1 2.042(6)
[2.013(7)], Ru1-N3 2.165(6) [2.175(6)], Ru1-N4 1.915(6) [1.900(6)], Ru1-C27carbonyl group
1.950(7) [1.945(7)].
Interestingly, during preparation of Ru-4, a very small amount (yield < 1%) of other compound
crystallized out of the reaction mixture. On the base of X-ray measurement, the structure of this
side product Ru-5 has been solved and refined (Figure 3).
Figure 3. Structure and crystallographic structure of unexpected by-product Ru-5. Selected bond
lengths in angstroms: Ru1-Cl1 2.3714(5), Ru1-Cl2 2.3522(6), Ru1-C1 1.983(2), Ru1-O1
2.175(2), Ru1-N3 2.187(2), Ru1-N4 1.938(2).
Due to some rearrangement within the molecule of the complex Ru-4, a product where
mesitylene group was bridged to the phenyl ring and nitrogen atom of a neighbouring moiety has
been established. As a result of this double bridging, six combined rings were created.
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In order to confirm that the complex Ru-4 contains the nitroso-acyl moiety, we have decided to
transform compound Ru-4 into its derivative containing PPh3 ligand. To achieve this goal,
triphenylphosphine was added to the DCM solution of the previously obtained compound Ru-4
and a new compound Ru-6 was afforded in 35% yield (Scheme 2).
Scheme 2. Synthesis of complex Ru-6.
Alternatively, compound Ru-6 can be obtained by the reaction between the commercially
available indenylidene complex containing PPh3 as a ligand (Umicore M20) and 2-nitrostyrene,
but also in this case the yield was low and reached only 30%. Fortunately in this case a crystal of
Ru-6 of good quality was obtained by crystallization from DCM/n-hexane mixture (Figure 4)
which allowed us to confirm the structure of the isolated compound. Unfortunately any attempts
to increase the yield of the desired catalysts Ru-4 and Ru-6 crashed and burned. Although a
complete conversion of both substrates was observed, due to the low stability of complexes
during the column chromatography it was impossible to obtain high yield even when silica gel
was replaced by aluminium oxide or Florisil.
On Scheme 3 a hypothetical mechanism of formation of complex Ru-4 is presented.
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MesN
NMes
SIMes
O-
O N+
+
Cl
NO2
Ph
Ru
Cl
Cl
Cl
- pyridine
Ru
py
Ph
-
A
M31
MesN
py
NMes
O
SIMes
RuCl
SIMes
O
+
N
O
B
O
+ pyridine
N
RuCl
O
N
H
Ru
Cl
Cl-
O
C
Ru-4
Scheme 3. Proposed mechanism of formation of a Ru-4 (SIMes = 1,3-dimesitylimidazolin-2-
ylidene).
In the first step, alkylidene ligands are exchanged with a subsequent elimination of the
pyridine moiety leading to compound A. Next, a rearrangement of the molecule takes place,
which results in the formation of a bicyclic system B, which, as a result of the chloride ion attack,
is then transformed into complex C. In the final stage, the resulting compound in reaction with
pyridine is converted into a catalyst Ru-4.
Figure 4. Crystallographic structure of the complex Ru-6. Selected bond lengths in angstroms:
Ru1-Cl1 2.4043(5), Ru1-P1 2.3861(5), Ru1-N3 1.911(2), Ru1-C19 2.142(2), Ru1-C47 carbonyl group
1.970(2).
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Here, we report the first structure of the nitroso-chelated ruthenium atom. The catalyst
molecules Ru-4 and Ru-6 crystallize in the C2/c and P-1 space groups of the monoclinic and
triclinic crystal systems, respectively. The crystal structure of the complex Ru-4 contains two
molecules of catalyst and two molecules of solvent (DCM) in the asymmetric unit. The molecules
of catalyst are not identical as they are differentiated by the N4 atom located in the five-
membered heterocyclic ring. This particular N4 atom is a part of nitroso group. This group is
always on the opposite site of the carbonyl group in this ring. In the first molecule, the nitroso
group is on the one side of the five-membered heterocyclic ring (molecule) and in the second
molecule it is on the other side of the ring (molecule). The position of the carbonyl group is
changing respectively. Different positions of nitroso and carbonyl groups are confirmed by of the
N=O and C=O bond lengths. The crystal structure of the complex Ru-6 contains only one
molecule of catalyst and one solvent molecule (DCM) in the asymmetric unit. Based on these two
X-ray structures, one should note that while in the complex Ru-4, the pyridine ligand occupies
the cis position relative to the NHC ligand, in Ru-6 the PPh3 ligand occupies the trans position.
However, both of conformations show the X-Ru-N angle (X=N3 for Ru-4 and Cl1 for Ru-6)
close to 180 degrees. Introduction of the pyridine ligand also changes the conformation of the
phenyl ring in the NHC ligand that rotates out of the ruthenium centre. Solution of crystal
structure of complex Ru-4 has revealed that there are two types of assignment of the nitrogen
atom position in the cyclic
η1-acyl group (as a consequence, two different molecules are
observed in the asymmetric unit). Nevertheless, in both structures the N-O and C-O bonds are
distinguishable. The length of the N-O bond is: 1.249(7)Å (molecule 1) and 1.267(7)Å (molecule
2) for the complex Ru-4 and 1.255(3)Å for Ru-6. The length of the C-O bond is: 1.209(9)Å in
the molecule 1 and 1.226(8)Å in the second molecule of the complex Ru-4 and 1.219(3)Å in the
complex Ru-6.
It is worth to mention that the Cambridge Structural Database does not contain similar
compounds as these studied in this work. The ruthenium atom connected directly with the nitroso
and carbonyl group is a unique molecular fragment (synthon).
All the relevant experimental details concerning the X-ray data collection for the complexes
Ru-4, Ru-5 and Ru-6 as well as selected geometrical parameters are presented in the ESI (see
Tables S1, S2, S3 and S4). CCDC 1584777-1584779 entries contain the supplementary
crystallographic data (CIF files) for this paper.
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Catalytic Performance Tests
As expected, due to the lack of benzylidene ligand, the newly obtained complexes Ru-4 and
Ru-6 were found to be inactive in model olefin metathesis reactions such as RCM of diethyl 2,2-
diallylmalonate and N,N-diallyl-4-methylbenzenesulfonamide, or CM between allyl benzene and
1,4-diacetoxy but-2-ene. Therefore, it was decided to explore other non-metathetical activities of
compounds Ru-4 and Ru-6, because such unusual compounds obtained “by accident” often
exhibited intriguing reactivity, inaccessible to standard catalysts. A good example of such
situation was the discovery of the decomposition of the ruthenium-based complexes in the
environment of primary alcohols [21-24], Mol [21], and Fogg [22] investigated the mechanistic
aspect of the influence of alcohols on the decomposition of Hoveyda-Grubbs type olefin
metathesis catalysts. In other studies Fogg discovered also that Grubbs first generation catalyst in
alcoholic solution in presence of Et3N decompose to hydridocarbonyl complex Ru-8 [23]. On the
other hand, Nolan while working on decomposition of indenylidene metathesis catalysts in
conditions similar to those used by Fogg and Mol obtained compound Ru-9 [24-26]. Complexes
Ru-8 and Ru-9 exhibited activity in many types of reactions including racemization of chiral
alcohols [24] or transfer hydrogenation [27-40]. In this context it is also worth mentioning
popular ruthenium-based transfer hydrogenation catalyst Ru-7 (see Figure 6) reported by Shvo
[41].
Figure 6. Selected transfer hydrogenation ruthenium-based catalysts.
Initially, our attention was focused on the reaction of transfer hydrogenation to obtain
secondary alcohols from ketones [25, 26]. The base, sodium hydroxide, has been chosen based on
previous literature reports since the effect of such reactant on transfer hydrogenation is well
known [42]. Solution of NaOH in isopropanol was added to given ketone and the reaction was
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carried out at 90 °C in a sealed vial for 24 hours (Scheme 4). The conversion was determined by
GC. Table 1 shows results of the reduction of different ketones.
Scheme 4. Transfer hydrogenations of ketones.
Table 1. Transfer hydrogenations of ketones.a
Entry
1
Substrate
Product
[Ru]
Conversion [%]b
96
Ru-6
2
14
<5c
95d
Ru-4
Ru-6
Ru-6
3
4
5
6
Ru-6
Ru-6
96
96
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a
Reaction conditions: 0.5 mol% of [Ru], 2.5 mol% of NaOH, isopropanol, 90 °C in a sealed
b
c
vial 24 h. Conversion was determined by GC using durene as an internal standard. Reaction
carried out without NaOH. d 0.25 mol% of Ru-6 was used.
Entries 1-4 showed reduction of acetophenone under different conditions. When 0.5 mol% of
Ru complex Ru-6 and 2.5 mol% of NaOH was used 96% conversion was reached (Entry 1) and
the same reaction conducted in the presence of 0.5 mol% of Ru-4 with the other conditions
unchanged gave only 14% yield (Entry 2). The absence of NaOH caused a drop of conversion to
less than 5% (Entry 3), while decreasing of Ru loading to 0.25 mol% had no significant influence
on the degree of conversion, 95% of the desired product was obtained (Entry 4). In entries 5 and
6 the reduction of 1-indanone and 1,3-indandione is presented. Also here, in both cases, almost
quantitative conversion was observed in the presence of Ru-6.
The next attempt to evaluate the applications of nitroso complexes was cycloisomerization
reaction. On the Scheme 5 an example of such a reaction, cycloisomerisation of
N,N-diallyl-4-
methylbenzenesulfonamide is presented. The transformation was performed in dry toluene at
80 °C for a given time (Table 2). Progress of reaction was monitored by GC.
Scheme 5. Cycloisomerization reaction N,N-diallyl-4-methylbenzenesulfonamide.a
Table 2. Cycloisomerization reaction of N,N-diallyl-4-methylbenzenesulfonamide.a
Entry
[Ru]
Ru-4
Ru-4
Ru-4
Ru-6
Ru-6
Ru-6
Time [h]
Conversion [%]b
1
2
3
4
5
6
24
48
72
24
48
72
76
84
90
27
28
30
a Reaction conditions: 5 mol% of [Ru], toluene 80 °C. b Conversion was determined by GC using
durene as an internal standard.
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In this case the reaction performed in the presence of ruthenium complex Ru-4 containing
pyridine as a ligand gave better result. In cycloisomerization reaction of
N,N-diallyl-4-
methylbenzenesulfonamide catalysed by Ru-4 the slow increase of conversion (from 76% to
90%) during 72 h was observed. When Ru-6 was applied after 24 hours the reaction reached
plateau around 30% and an increase of the reaction time by a further two days did not result in
almost any improvement in the conversion.
Next the investigation of activity of complexes Ru-4 and Ru-6 in ring opening metathesis
polymerization (ROMP) was performed. As a model substrate endo,exo-bicyclo[2.2.1]hept-5-
ene-2,3-dicarboxylic acid dimethyl ester (1) was chosen (Scheme 6). We selected this reaction for
benchmarking a novel initiator system [43-48]. Conversion of this transformation was determined
by 1H NMR spectroscopy.
Scheme 6. ROMP of endo,exo-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid dimethyl ester (1).
At the beginning polymerization was carried out in refluxing DCM without using any
additives (Table 3, Entry 1-2) and neither of the two complexes (Ru-4 and Ru-6) transformed 1
into the desired poly-1 product. However, when under the same conditions
1
(trimethylsilyl)diazomethane was added (1 equiv. related to ruthenium complex) H NMR
analysis showed conversion 38% and 47% for complexes Ru-4 and Ru-6 respectively (Entry 3-
4). In entry 5 the solvent was changed from dichloromethane to toluene and the temperature of
reaction was raised to 80°C and as a result almost full conversion was obtained.
Table 3. ROMP of endo,exo-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid dimethyl ester (1).a
Entry
[Ru]
Ru-4
Ru-6
Ru-4
Ru-6
Ru-4
Additive
-
Conditions
DCM, 40°C
DCM, 40°C
DCM, 40°C
DCM, 40°C
Toluene, 80°C
Conv. (%)b
1
2
3
4
5
0
0
-
TMS-CHN2
TMS-CHN2
TMS-CHN2
38
47
>98
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a Reaction conditions: [Ru]/1 = 1:300; Reaction time = 24 h; [Ru]/Additive = 1:1. b Conversion
was determined by 1H NMR.
As stated above, the reactions of endo,exo-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid
dimethyl ester (1) catalysed by Ru-4 and Ru-6 in the presence of (trimethylsilyl)diazomethane
were carried out in NMR tube. A detailed analysis of the spectrum should enable active species to
1
be identified, if such would appear during the reaction. However in H NMR spectra in region
22-14 ppm, no characteristic signal from alkylidene proton were observed.
In the last stage of research, inspired by Nolan's works [24]. we decided to check whether Ru-
4 and Ru-6 complexes could be utilized for racemisation of chiral alcohols. For this purpose, we
stirred an optically pure (99.5% ee) substrate (S)-1-(naphthalen-2-yl)ethan-1-ol in the presence of
one of above mentioned catalysts and potassium tert-butanolate in toluene. After 24 hours the
optical purity of alcohol was examined using HPLC (Chiralcel® OJ; HEX:IPA 95:5; 1 mL/min;
254 nm).
Scheme 7. Racemisation of (S)-1-(naphthalen-2-yl)ethan-1-ol.
When racemization was carried out in the presence of Ru-4, only a slight decrease in optical
purity of 1-(naphthalen-2-yl)ethane-1-ol was observed (it dropped down from 99.5 to 90%). In
the same process conducted in the presence of Ru-6 no racemisation was observed and the
optical purity of alcohol remained at the same high level, 99%.
Conclusions
During the reaction between third generation indenylidene catalyst M31 and 2-nitrostyrene, a
new nitroso-chelated cyclic η1-acylruthenium(II) complexes Ru-4 and Ru-6 were unexpectedly
obtained. Their structures were confirmed by spectroscopic techniques as well as, after
transformation into a derivative containing triphenylphosphine ligand, by X-Ray crystallography.
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Due to the lack of benzylidene ligand the new complexes did not show any activity in standard
metathesis reactions, however in the presence of (trimethylsilyl)diazomethane they led to good
results in ROMP of endo,exo-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid dimethyl ester 1.
Despite both of studied complexes were not active in a base-promoted racemisation of chiral
alcohols [24], complex Ru-4 exhibited high activity in cycloisomerization of
N,N-diallyl-4-
methylbenzenesulfonamide, while complex Ru-6 provided good results in transfer hydrogenation
reactions leading to secondary alcohols.
Experimental section
General conditions. The catalyst preparation was carried out under argon in pre-dried
glassware using Schlenk techniques or in a glove box. The anhydrous DCM was dried by
distillation over CaH2 and was transferred under argon. For polymerization toluene without
styrene stabilizer from Sigma Aldrich (Chromasolv for HPLC, 99.9%) was used. Column
chromatography was performed using Sigma Aldrich silica gel 60 (230-400 mesh). Analytical
thin-layer chromatography (TLC) was performed using silica gel 60 F254 pre-coated plates (0.25
mm thickness) with a fluorescent indicator. NMR spectra were recorded on Varian; Mercury 400
MHz, in CDCl3; chemical shifts (δ) are given in ppm relative to TMS, coupling constants are (J)
in Hz. MS (ESI) spectra were recorded by Quattro LC (triple quadrupole mass spectrometer). GC
measurements were done on PE Clarus 580 with InertCap 5MS-Sil column and GC/MS on PE
Clarus 680/600S with InertCap 5 column. All other commercially available chemicals were used
as received.
Synthesis of Compound Ru-4.
To 748.0 mg (1 mmol) of [1,3-Bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene]dichloro(3-
phenyl-1H-inden-1-ylidene)(pyridyl) ruthenium(II) (M31) in toluene (13 mL) 2-nitrostyrene
(298.0 mg, 2 mmol) in toluene (2 mL) was added at 80°C. After 5 min the mixture was cooled to
room temperature and solvent was evaporated. Residue was purified by silica gel column
chromatography (eluent: ethyl acetate/cyclohexane 10% v/v
→ ethyl acetate). Violet fraction was
collected. After evaporation residue was recrystallized twice from CH2Cl2/n-hexane to give 310.0
mg of dark violet crystalline solid (48%).
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1H NMR (400 MHz, CDCl3)
δ: 8.47–8.37 (m, 1H), 8.07 (s, 1H), 7.60–7.38 (m, 2H), 7.25–7.12
(m, 1H), 7.07–6.95 (m, 3H), 6.85–6.75 (m, 3H), 6.60–6.42 (m, 1H), 6.17 (s, 1H), 4.00–3.75 (m,
4H), 2.50–2.05 (m, 15H), 1.76 (s, 3H) ppm.
13C NMR (100 MHz, CDCl3)
δ: 238.0, 209.1, 171.4, 153.1, 149.6, 148.3, 138.0, 135.9, 135.8,
135.6, 135.2, 130.2, 129.6, 129.0, 128.2, 122.8, 118.6, 107.8, 53.4, 51.8, 31.4, 22.5, 20.7, 18.3,
17.5, 14.0 ppm.
IR:
ν
= 3495, 2913, 1617, 1605, 1483, 1445, 1354, 1263, 898, 850, 756, 690, 575, 521 cm−1.
calcd. for C33H35N4O2Ru: [M-Cl-] 621.1804, found 621.1797.
HRMS (ESI): m/z
Synthesis of compound Ru-6.
Method A: To a solution of complex Ru-4 (87.8 mg, 0.13 mmol) in CH2Cl2 (5 mL)
triphenylphosphine (68.2 mg, 0.26 mmol) was added. The mixture was stirred at room
temperature for 30 min and then evaporated. Residue was purified by silica gel column
chromatography (eluent: ethyl acetate/cyclohexane 3:7 v/v). Violet fraction was collected and
evaporated. Residue was recrystallized twice from CH2Cl2/n-hexane to give 40 mg of violet
crystalline solid (35%).
Method B: To a solution of 93.2 mg (0.1 mmol) [1,3-Bis(2,4,6-trimethylphenyl)-2-
imidazolidinylidene]dichloro(3-phenyl-1H-inden-1-ylidene)(triphenylphosphine)ruthenium(II)
(M20) in toluene (1 mL) 2-nitrostyrene (29.8 mg, 0.2 mmol) in toluene (1 mL) was added at
80°C. The mixture was stirred for 45 min and then cooled to room temperature and evaporated.
Residue was purified by silica gel column chromatography (eluent: ethyl acetate/cyclohexane 1:9
→
3:7 v/v). Violet fraction was collected and evaporated. Residue was recrystallized twice from
CH2Cl2/n-hexane to give 25 mg of violet crystalline solid (30%).
1H NMR (400 MHz, CDCl3)
δ: 7.15–7.09 (m, 3H), 7.06–6.97 (m, 14H), 6.94–6.91 (m, 1H),
6.89–6.85 (m, 2H), 6.75–6.70 (m, 1H), 6.50–6.33 (m, 2H), 3.95–3.80 (m, 4H), 2.46 (s, 6H), 2.30–
1.90 (m, 12H) ppm.
13C NMR (100 MHz, CDCl3)
134.0, 130.4, 130.3, 130.0, 129.3, 129.2, 128.0, 127.6, 127.5, 118.9, 109.8, 51.8, 21.0, 18.8 ppm.
δ: 234.0, 233.9, 207.0, 205.8, 170.8, 144.5, 137.6, 135.2, 134.1,
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31P NMR (160 MHz, CDCl3)
δ: 21.4 ppm.
IR: = 3053, 2913, 1623, 1479, 1433, 1349, 1266, 1137, 1091, 1027, 997, 898, 849, 756, 695,
ν
650, 512 cm−1.
HRMS (ESI):
X-ray Analysis
m/z
calcd. for C46H45N3O2PRu: [M-Cl-] 804.2293, found 804.2289.
The single crystal diffraction data collection for complex Ru-4 and complex Ru-6 was
performed on a single crystal Oxford Diffraction diffractometers with graphite-monochromated
MoK
flow apparatus and measurements were conducted at 100K. In the case of the complex Ru-5, data
collection was performed on a SuperNova diffractometer with mirror-monochromated CuK
α radiation. The diffractometers were equipped with an Oxford Cryosystems nitrogen gas-
α
radiation. For all measurements multi-scan absorption correction was applied. The CrysAlis PRO
program was used for the data collection and its further reduction [49]. The structures were
solved by direct methods and refined using SHELXL [50] program in cooperation with the
Olex2 program [51]. The refinements were based on F2. Some geometric and ADP restrains were
required during refinement of the complex Ru-4.
The lattice parameters and the final R-indices obtained for the refinement of the structures of
complexes Ru-4, Ru-5 and Ru-6 are presented in Table S1. Selected geometrical parameters for
these structures are shown in Table S2, Table S3 and Table S4, respectively.
Typical Procedure for the Catalytic Transfer Hydrogenation of Ketones.
In a glovebox to 4 mL vial appropriate ketone (0.5 mmol) and durene as an internal standard
(0.5 mmol) was added followed by i-PrOH (1.75 mL). Next the respective catalyst (0.25–0.5
mmol) was added as a solid followed by NaOH (0.0125 mmol) in 0.25 mL
stirred at 90°C for 24 h. Conversion was determined by GC.
i-PrOH. Mixture was
Procedure for the Cycloisomerization.
In a glovebox to 4 mL vial N,N-diallyl-4-methylbenzenesulfonamide (0.1 mmol) and durene as
an internal standard (0.1 mmol) was added followed by toluene (3 mL). Next the respective
catalyst (0.05 mmol) was added as a solid. Mixture was stirred at 80–90°C, and the samples in
different time intervals were taken. Conversion was determined by GC.
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Typical Procedure for the ROMP of endo,exo-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic
acid dimethyl ester 1.
To the respective catalyst (0.00159 mmol) dissolved in a proper solvent (2 mL) was added a
solution of (trimethylsilyl)diazomethane (0.5 M in toluene, 3 µL, 0.00159 mmol). The mixture
was transferred to the monomer 1 (0.476 mmol) dissolved in proper solvent (2 mL). Reaction was
carried out for 24 h. The reaction was quenched by the addition of an excess of ethyl vinyl ether.
Conversion was determined by 1H NMR.
Typical Procedure for Racemisation of (S)-1-(Naphthalen-2-yl)ethan-1-ol.
To the respective catalyst (0.005 mmol) potassium tert-butoxide (0.00625 mmol, 0.25 mL,
0.025M solution in toluene) was added followed by solution of ( )-1-(Naphthalen-2-yl)ethan-1-ol
S
(86 mg, 0.5 mmol) in toluene (0.75 mL). The reaction was carried out at room temperature for 24
h and then was quenched by the addition of an excess of ethyl vinyl ether. Racemisation was
determined by HPLC (ChiralCel®, hexane:isopropanol 95:5, 1.0 mL/min, 254 nm).
Acknowledgments
Authors are grateful to the National Science Centre (Poland) for the NCN MAESTRO Grant
No. DEC-2012/04/A/ST5/00594. The study was carried out at the Biological and Chemical
Research Centre, University of Warsaw, established within the project co-financed by European
Union from the European Regional Development Fund under the Operational Programme
Innovative Economy, 2007−2013. The authors thank Mr. Grzegorz Szczepaniak for an inspiring
discussion on the mechanism of forming of the complex Ru-4.
Supplementary data
The supporting information associated with this article can be found at
Corresponding author
* E-mail (K. Grela): prof.grela@gmail.com
* E-mail (A. Kajetanowicz): anna.kajetanowicz@gmail.com
References
16

ACCEPTED MANUSCRIPT
[1] C. Wang, C. Li, X. Wu, A. Pettman, J. Xiao, Angew. Chem. Int. Ed., 48 (2009) 6524-6528.
[2] F. Alonso, P. Riente, M. Yus, Acc. Chem. Res., 44 (2011) 379-391.
[3] R.H. Grubbs, A.G. Wenzel, D.J. O'Leary, E. Khosravi, Handbook of Metathesis, Wiley-VCH,
Weinheim, 2014.
[4] K. GrelaꢀOlefin Metathesis: Theory and Practice, John Wiley & Sons, Inc., Hoboken, 2014.
[5] https://www.nobelprize.org/nobel_prizes/chemistry/laureates/2005/.
[6] R. Gawin, A. Kozakiewicz, P.A. Gu
Ed., 56 (2017) 981-986.
ńka, P. Dąbrowski, K. Skowerski, Angew. Chem. Int.
[7] D.R. Anderson, T. Ung, G. Mkrtumyan, G. Bertrand, R.H. Grubbs, Y. Schrodi,
Organometallics, 27 (2008) 563-566.
[8] P. Małecki, K. Gajda, O. Ablialimov, M. Mali
K. Grela, Organometallics, 36 (2017) 2153-2166.
ńska, R. Gajda, K. Woźniak, A. Kajetanowicz,
[9] M. Rouen, P. Queval, E. Borré, L. Falivene, A. Poater, M. Berthod, F. Hugues, L. Cavallo, O.
Baslé, H. Olivier-Bourbigou, M. Mauduit, ACS Catal., 6 (2016) 7970-7976.
[10] T.T. Nguyen, M.J. Koh, X. Shen, F. Romiti, R.R. Schrock, A.H. Hoveyda, Science, 352
(2016) 569-575.
[11] X. Shen, T.T. Nguyen, M.J. Koh, D. Xu, A.W.H. Speed, R.R. Schrock, A.H. Hoveyda,
Nature, 541 (2017) 380-385.
[12] G. Occhipinti, F.R. Hansen, K.W. Törnroos, V.R. Jensen, J. Am. Chem. Soc., 135 (2013)
3331-3334.
[13] S.M. Bronner, M.B. Herbert, P.R. Patel, V.M. Marx, R.H. Grubbs, Chem. Sci., 5 (2014)
4091-4098.
[14] A. Michrowska, R. Bujok, S. Harutyunyan, V. Sashuk, G. Dolgonos, K. Grela, J. Am.
Chem. Soc., 126 (2004) 9318-9325.
[15] K. Grela, S. Harutyunyan, A. Michrowska, Angew. Chem. Int. Ed., 41 (2002) 4038-4040.
[16] O.M. Demchuk, K.M. Pietrusiewicz, A. Michrowska, K. Grela, Org. Lett., 5 (2003) 3217-
3220.
[17] A. Michrowska, M. Bieniek, M. Kim, R. Klajn, K. Grela, Tetrahedron, 59 (2003) 4525-
4531.
[18] A.K. Chatterjee, T.-L. Choi, D.P. Sanders, R.H. Grubbs, J. Am. Chem. Soc., 125 (2003)
11360-11370.
[19] A. Jana, K. Grela, Org. Lett., 19 (2017) 520-523.
[20] T.K. Olszewski, M. Bieniek, K. Skowerski, K. Grela, Synlett, 24 (2013) 903-919.
[21] Maarten B. Dinger, Johannes C. Mol, Eur. J. Inorg. Chem., 2003 (2003) 2827-2833.
[22] N.J. Beach, J.A.M. Lummiss, J.M. Bates, D.E. Fogg, Organometallics, 31 (2012) 2349-
2356.
[23] N.J. Beach, K.D. Camm, D.E. Fogg, Organometallics, 29 (2010) 5450-5455.
[24] S. Manzini, C.A. Urbina-Blanco, A. Poater, A.M.Z. Slawin, L. Cavallo, S.P. Nolan, Angew.
Chem. Int. Ed., 51 (2012) 1042-1045.
[25] S. Manzini, D.J. Nelson, T. Lebl, A. Poater, L. Cavallo, A.M.Z. Slawin, S.P. Nolan, Chem.
Commun., 50 (2014) 2205-2207.
[26] S. Manzini, C.A.U. Blanco, S.P. Nolan, Adv. Synth. Catal., 354 (2012) 3036-3044.
[27] M.-O. Simon, C.-J. Li, Chem. Soc. Rev., 41 (2012) 1415-1427.
[28] R. Malacea, R. Poli, E. Manoury, Coord. Chem. Rev., 254 (2010) 729-752.
[29] M. Bartók, Chem. Rev., 110 (2010) 1663-1705.
[30] R.H. Morris, Chem. Soc. Rev., 38 (2009) 2282-2291.
[31] C. Wang, X. Wu, J. Xiao, Broader, Chem. Asian J., 3 (2008) 1750-1770.
17

ACCEPTED MANUSCRIPT
[32] T. Ikariya, A.J. Blacker, Acc. Chem. Res., 40 (2007) 1300-1308.
[33] X. Wu, J. Xiao, Chem. Commun., (2007) 2449-2466.
[34] C.M. Moore, N.K. Szymczak, Chem. Commun., 49 (2013) 400-402.
[35] J. Li, Y. Tang, Q. Wang, X. Li, L. Cun, X. Zhang, J. Zhu, L. Li, J. Deng, J. Am. Chem. Soc.,
134 (2012) 18522-18525.
[36] I. Sorribes, G. Wienhöfer, C. Vicent, K. Junge, R. Llusar, M. Beller, Angew. Chem. Int. Ed.,
51 (2012) 7794-7798.
[37] M.A. Ariger, E.M. Carreira, Org. Lett., 14 (2012) 4522-4524.
[38] K.M. Steward, E.C. Gentry, J.S. Johnson, J. Am. Chem. Soc., 134 (2012) 7329-7332.
[39] H. Vázquez-Villa, S. Reber, M.A. Ariger, E.M. Carreira, Angew. Chem. Int. Ed., 50 (2011)
8979-8981.
[40] L.T. Ghoochany, S. Farsadpour, Y. Sun, W.R. Thiel, Eur. J. Inorg. Chem., 2011 (2011)
3431-3437.
[41] Y. Shvo, D. Czarkie, Y. Rahamim, D.F. Chodosh, J. Am. Chem. Soc., 108 (1986) 7400-
7402.
[42] S.U. Sonavane, R.V. Jayaram, Synth. Commun., 33 (2003) 843-849.
[43] X. Gstrein, D. Burtscher, A. Szadkowska, M. Barbasiewicz, F. Stelzer, K. Grela, C. Slugovc,
J. Polym. Sci. A, 45 (2007) 3494-3500.
[44] J. Broggi, C.A. Urbina-Blanco, H. Clavier, A. Leitgeb, C. Slugovc, A.M.Z. Slawin, S.P.
Nolan, Chem. Eur. J., 16 (2010) 9215-9225.
[45] C.A. Urbina-Blanco, A. Leitgeb, C. Slugovc, X. Bantreil, H. Clavier, A.M.Z. Slawin, S.P.
Nolan, Chem. Eur. J., 17 (2011) 5045-5053.
[46] A. Leitgeb, A. Szadkowska, M. Michalak, M. Barbasiewicz, K. Grela, C. Slugovc, J. Polym.
Sci. A, 49 (2011) 3448-3454.
[47] C.A. Urbina-Blanco, X. Bantreil, J. Wappel, T.E. Schmid, A.M.Z. Slawin, C. Slugovc,
C.S.J. Cazin, Organometallics, 32 (2013) 6240-6247.
[48] A. Kozłowska, M. Dranka, J. Zachara, E. Pump, C. Slugovc, K. Skowerski, K. Grela, Chem.
Eur. J., 20 (2014) 14120-14125.
[49] C.S.s. Xcalibur/SuperNova CCD system, Version 1.171.36.32; Agilent Technologies UK
Ltd.: Oxford, UK,. in, 2012.
[50] G. Sheldrick, Acta Crystallogr. A, 71 (2015) 3-8.
[51] O.V. Dolomanov, L.J. Bourhis, R.J. Gildea, J.A.K. Howard, H. Puschmann, J. Appl.
Crystallogr., 42 (2009) 339-341.
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Highlights:




Nitroso- chelated acylruthenium complexes were prepared and fully
characterized
The unique structure of the complexes has been confirmed by X-ray structural
analysis
Ru-complex exhibit good activity in transfer hydrogenations of aromatic
ketones
Nitroso- chelated acylruthenium complexes catalyze ring opening metathesis
polymerization in the presence of (trimethylsilyl)diazomethane